A conveyor belt generally has a configuration in which an upper cover rubber is layered on an outer peripheral side of a core formed from a canvas layer or a steel cord layer, and a lower cover rubber is layered on an inner peripheral side of the core. An object to be conveyed is fed and placed onto the upper cover rubber and conveyed. The upper cover rubber is subject to great impact depending on the fed object to be conveyed. The impact causes damage to the upper cover rubber to progress over time. The damage to the upper cover rubber is significant in the case where the object to be conveyed has a sharp projection on a surface of the object to be conveyed.
The conveying speed of the conveyor belt is different from the speed of the fed object to be conveyed in a belt conveying direction. As a result, friction generates between the upper cover rubber and the object to be conveyed. Friction also generates between the upper cover rubber and the object to be conveyed while the object to be conveyed is conveyed. The friction causes wear on the upper cover rubber to progress over time.
When the damage and wear caused by the impact reach the core, the conveyor belt cannot be used. Accordingly, the upper cover rubber having improved impact resistance and wear resistance can extend the service life of the conveyor belt.
Conventionally, various conveyor belts have been proposed. Such conveyor belts achieve good wear resistance and impact resistance in a compatible manner (For example, Japanese Unexamined Patent Application Publication No. 2013-107729A). Including the conveyor belt proposed in Japanese Unexamined Patent Application Publication No. 2013-107729A, conveyor belts are known that have a configuration in which special rubber composition having good wear resistance and impact resistance is used as the upper cover rubber (paragraph [0145] of Japanese Unexamined Patent Application Publication No. 2013-107729A). However, achieving good wear resistance and impact resistance in a compatible manner with single rubber composition is difficult. Conventional conveyor belts have a tendency in that one or both characteristics are improved insufficiently.